Transmog scrolls drop chance

So far, I've been told these can drop from battleground wins.

While farming honor as a fresh 80, I've been winning quite a few BGs for 3-4 days in a row. Up to 10 per day.

So far, I haven't seen even one player getting any of these (considering the fact oneBG instance can contain from 10 to 30-40 people at once).

The question is: how realistic is the chance to get 5-6 of these to form at least ONE t-mog set? How big is the chance to get the scroll? 1 per 100? 1 per 1000? Any info would be helpful.

P.S. I can't purchase these scrolls in coin shop due to very weird UI bug (blank page opens when I choose an item). Cleared cash, used other browsers, nothing helped.

P.P.S. Would be even better if they could make the scrolls BoE.. Why not?

U wont see when other players getting scrolls. I got about 20 with more characters (with few 10000 hks :D so drop change rly low)